bevy_color/
color_gradient.rs

1use crate::Mix;
2use bevy_math::curve::{
3    cores::{EvenCore, EvenCoreError},
4    Curve, Interval,
5};
6
7/// A curve whose samples are defined by a collection of colors.
8#[derive(Clone, Debug)]
9#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
10#[cfg_attr(feature = "bevy_reflect", derive(bevy_reflect::Reflect))]
11pub struct ColorCurve<T> {
12    core: EvenCore<T>,
13}
14
15impl<T> ColorCurve<T>
16where
17    T: Mix + Clone,
18{
19    /// Create a new [`ColorCurve`] from a collection of [mixable] types. The domain of this curve
20    /// will always be `[0.0, len - 1]` where `len` is the amount of mixable objects in the
21    /// collection.
22    ///
23    /// This fails if there's not at least two mixable things in the collection.
24    ///
25    /// [mixable]: `Mix`
26    ///
27    /// # Example
28    ///
29    /// ```
30    /// # use bevy_color::palettes::basic::*;
31    /// # use bevy_color::Mix;
32    /// # use bevy_color::Srgba;
33    /// # use bevy_color::ColorCurve;
34    /// # use bevy_math::curve::Interval;
35    /// # use bevy_math::curve::Curve;
36    /// let broken = ColorCurve::new([RED]);
37    /// assert!(broken.is_err());
38    /// let gradient = ColorCurve::new([RED, GREEN, BLUE]);
39    /// assert!(gradient.is_ok());
40    /// assert_eq!(gradient.unwrap().domain(), Interval::new(0.0, 2.0).unwrap());
41    /// ```
42    pub fn new(colors: impl IntoIterator<Item = T>) -> Result<Self, EvenCoreError> {
43        let colors = colors.into_iter().collect::<Vec<_>>();
44        Interval::new(0.0, colors.len().saturating_sub(1) as f32)
45            .map_err(|_| EvenCoreError::NotEnoughSamples {
46                samples: colors.len(),
47            })
48            .and_then(|domain| EvenCore::new(domain, colors))
49            .map(|core| Self { core })
50    }
51}
52
53impl<T> Curve<T> for ColorCurve<T>
54where
55    T: Mix + Clone,
56{
57    #[inline]
58    fn domain(&self) -> Interval {
59        self.core.domain()
60    }
61
62    #[inline]
63    fn sample_clamped(&self, t: f32) -> T {
64        // `EvenCore::sample_with` clamps the input implicitly.
65        self.core.sample_with(t, T::mix)
66    }
67
68    #[inline]
69    fn sample_unchecked(&self, t: f32) -> T {
70        self.sample_clamped(t)
71    }
72}
73
74#[cfg(test)]
75mod tests {
76    use super::*;
77    use crate::{palettes::basic, Srgba};
78
79    #[test]
80    fn test_color_curve() {
81        let broken = ColorCurve::new([basic::RED]);
82        assert!(broken.is_err());
83
84        let gradient = [basic::RED, basic::LIME, basic::BLUE];
85        let curve = ColorCurve::new(gradient).unwrap();
86
87        assert_eq!(curve.domain(), Interval::new(0.0, 2.0).unwrap());
88
89        let brighter_curve = curve.map(|c: Srgba| c.mix(&basic::WHITE, 0.5));
90
91        [
92            (-0.1, None),
93            (0.0, Some([1.0, 0.5, 0.5, 1.0])),
94            (0.5, Some([0.75, 0.75, 0.5, 1.0])),
95            (1.0, Some([0.5, 1.0, 0.5, 1.0])),
96            (1.5, Some([0.5, 0.75, 0.75, 1.0])),
97            (2.0, Some([0.5, 0.5, 1.0, 1.0])),
98            (2.1, None),
99        ]
100        .map(|(t, maybe_rgba)| {
101            let maybe_srgba = maybe_rgba.map(|[r, g, b, a]| Srgba::new(r, g, b, a));
102            (t, maybe_srgba)
103        })
104        .into_iter()
105        .for_each(|(t, maybe_color)| {
106            assert_eq!(brighter_curve.sample(t), maybe_color);
107        });
108    }
109}
bevy_color/color_gradient.rs

bevy_color/
color_gradient.rs
